Co-reporter:Ya-Kun Dou, Yang Chen, Xi-Wen He, Wen-You Li, Yu-Hao Li, and Yu-Kui Zhang
Analytical Chemistry November 7, 2017 Volume 89(Issue 21) pp:11286-11286
Publication Date(Web):October 16, 2017
DOI:10.1021/acs.analchem.7b01644
Silicon nanoparticles (Si NPs) have been widely used in fluorescence imaging. However, rigorous synthesis conditions and the single modality imaging limit the further development of Si NPs in the field of biomedical imaging. Here, we reported a method for synthesizing water-dispersible Mn2+ functionalized Si NPs (Mn–Si NPs) under mild experimental conditions for fluorescence and magnetic resonance dual-modality imaging. The whole synthesis process was completed under room temperature and atmospheric pressure, and no special and expensive equipment was required. The synthetic nanoparticles, with favorable pH stability, NaCl stability, photostability, and low toxicity, emitted green fluorescence (512 nm). At the same time, the nanoparticles also demonstrated excellent magnetic resonance imaging ability. In vitro, their T1-weighted magnetic resonance imaging effect was obvious, and the value of longitudinal relaxation degree r1 reached 4.25 mM–1 s–1. On the basis of their good biocompatibility, Mn–Si NPs were successfully used for the fluorescence imaging as well as magnetic resonance imaging in vivo.
Co-reporter:Yang Liu, Gao-Fei Tian, Xi-Wen He, Wen-You Li and Yu-Kui Zhang
Journal of Materials Chemistry A 2016 vol. 4(Issue 7) pp:1276-1283
Publication Date(Web):13 Jan 2016
DOI:10.1039/C5TB02322J
The development of ideal contrast agents was of great importance for multimodal imaging. However, the simple combination of different contrast components always needed long-time preparation and a tough reaction environment. In this study, we introduced a one-step microwave-assisted approach to synthesize lysozyme-capped gold nanoclusters (Lys–Au NCs) rapidly instead of traditional conditions. Irradiation with continuous microwave power shortened the reaction time from several hours to one hour and generated a large red shift (50 nm) of the fluorescence emission. The ultrasmall Lys–Au NCs showed excellent properties, including high quantum yield (19.61%), good stability, low cytotoxicity and good biocompatibility. This eco-friendly nanoprobe provided significant contrast signals in both NIRF (near-infrared fluorescence) and CT (X-ray computed tomography) in vivo imaging. Further conjugation with folic acid made the nanoprobe favorable for targeted fluorescence imaging of cancer cells and tumor-bearing mice.
Co-reporter:Ya-Ping Qin, Dong-Yan Li, Xi-Wen He, Wen-You Li, and Yu-Kui Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 16) pp:10155
Publication Date(Web):April 6, 2016
DOI:10.1021/acsami.6b00794
A novel epitope molecularly imprinted polymer on the surface of magnetic carbon nanotubes (MCNTs@EMIP) was successfully fabricated to specifically recognize target protein cytochrome c (Cyt C) with high performance. The peptides sequences corresponding to the surface-exposed C-terminus domains of Cyt C was selected as epitope template molecule, and commercially available zinc acrylate and ethylene glycol dimethacrylate (EGDMA) were employed as functional monomer and cross-linker, respectively, to synthesize MIP via free radical polymerization. The epitope was immobilized via metal chelation and six-membered ring formed between the functional monomer and the hydroxyl and amino groups of the epitope. The resulting MCNTs@EMIP exhibited specific recognition ability toward target Cyt C including more satisfactory imprinting factor (about 11.7) than that of other reported imprinting methods. In addition, the MCNTs@EMIP demonstrated a high adsorption amount (about 780.0 mg g–1) and excellent selectivity. Besides, the magnetic property of the support material made the processes easy and highly efficient by assistance of an external magnetic field. High-performance liquid chromatography analysis of Cyt C in bovine blood real sample and protein mixture indicated that the specificity was not affected by other competitive proteins, which forcefully stated that the MCNTs@EMIP had potential to be applied in bioseparation area. In brief, this study provided a new protocol to detect target protein in complex sample via epitope imprinting approach and surface imprinting strategy.Keywords: cytochrome c; epitope imprinting; magnetic carbon nanotubes; metal chelation and six-membered ring; molecularly imprinted polymer; protein recognition
Co-reporter:Hong-Li Ye, Shi-Jiao Cai, Si Li, Xi-Wen He, Wen-You Li, Yu-Hao Li, and Yu-Kui Zhang
Analytical Chemistry 2016 Volume 88(Issue 23) pp:
Publication Date(Web):October 31, 2016
DOI:10.1021/acs.analchem.6b03209
Silicon nanoparticles (SiNPs) have been reported to be synthesized by microwave-assisted methods under high pressure. However, there is still a lack of knowledge about the synthesis of SiNPs via microwave-assisted methods under normal pressure. Here we developed a new, facile, one-pot microwave-assisted method for the synthesis SiNPs (∼4.2 nm) with excellent water solubility under normal pressure by employing glycerol as the solvent. Furthermore, glycerol might be responsible for the photoluminescence quantum yield (PLQY) value up to 47% for the resultant SiNPs. The use of organic solvent could afford less nanoparticle surface defects compared with those prepared in aqueous solution, thus improving the fluorescent efficiency. The as-prepared SiNPs simultaneously featured bright blue-green fluorescence, long lifetime (∼12.8 ns), obvious up-conversion luminescence originating from two-photon absorption, superbly strong photostability, and favorable low toxicity. As a satisfactory probe, the as-synthesized SiNPs were successfully applied in fluorescence imaging of human cervical carcinoma cell lines (HeLa) and zebrafish.
Co-reporter:Fei Zhang, Xiu-Qi Kong, Qiong Li, Ting-Ting Sun, Chao Chai, Wen Shen, Zhang-Yong Hong, Xi-Wen He, Wen-You Li, Yu-Kui Zhang
Talanta 2016 Volume 148() pp:108-115
Publication Date(Web):1 February 2016
DOI:10.1016/j.talanta.2015.10.046
•We prepared CdTe@GdS nanoparticles by a facile room-temperature approach.•It can be synthesized in aqueous solution directly.•The nanoparticles showed excellent fluorescent and magnetic properties.•The biocompatibility of CdTe@GdS was increased by the protection of the GdS shell.•The CdTe@GdS nanoparticles have been successfully employed for dual-modal imaging.Multimodal imaging has made great contribution for diagnosis and therapy of disease since it can provide more effective and complementary information in comparison to any single imaging modality. The design and fabrication of fluorescent-magnetic nanoparticles for multimodal imaging has rapidly developed over the years. Herein, we demonstrate the facile synthesis of GdS coated CdTe nanoparticles (CdTe@GdS NPs) as multimodal agents for fluorescence (FL) and T1-weighted magnetic resonance (MR) imaging. These nanoparticles obtain both prominent fluorescent and paramagnetic properties by coating the GdS shell on the surface of CdTe core via a simple room-temperature route in aqueous solution directly. It is shown that the as-prepared CdTe@GdS NPs have high quantum yield (QY) value of 12% and outstanding longitudinal relaxation rate (r1) of 11.25 mM s−1, which allow them to be employed as FL/MR dual-modal imaging contrast agents. They also exhibit small particle size of 5 nm, excellent colloidal stability and low cellular toxicity for concentrations up to 750 μg mL−1. In addition, with the conjugation of folic acid, the nanoparticles were successfully used for tumor-targeted FL/MR dual-modal imaging in vitro and in vivo.CdTe@GdS nanoparticles were synthesized by a facile room-temperature approach in aqueous solution directly and successfully employed as a probe for fluorescence/magnetic resonance dual-modal imaging in vivo.
Co-reporter:Dong-Yan Li, Xue-Mei Zhang, Yun-Jing Yan, Xi-Wen He, Wen-You Li, Yu-Kui Zhang
Biosensors and Bioelectronics 2016 Volume 79() pp:187-192
Publication Date(Web):15 May 2016
DOI:10.1016/j.bios.2015.12.016
•A thermo-sensitive receptor CDs/SiO2/MIP was fabricated.•The CDs/SiO2/MIP with double templates exhibited higher imprinting effect.•The CDs/SiO2/MIP based on CDs and epitope approach was first reported.A new type of thermo-sensitive receptor carbon dots/SiO2/molecularly imprinted polymer (CDs/SiO2/MIP) was prepared by surface imprinting procedure and the epitope approach. The synthetic CDs/SiO2/MIP was able to selectively capture target protein with fluorescence quenching via the special interaction between them and the recognition cavities. The receptor exhibited the linear fluorescence quenching to cytochrome c (cyt c) in the range of 0.1–40 μM, and the detection limit was 89 nM. The precision for five replicate detection of cyt c at 20 μM was 3.11%. Moreover, the receptor owned the temperature-sensitive element that allowed for swelling and shrinking in response to temperature changes to realize recognition of the target cytochrome c. The proposed strategy revealed the feasibility of fabrication of a thermo-sensitive imprinted polymer based on CDs and surface imprinting procedure and the epitope approach.
Co-reporter:Tong Zhao, Xi-Wen He, Wen-You Li and Yu-Kui Zhang
Journal of Materials Chemistry A 2015 vol. 3(Issue 11) pp:2388-2394
Publication Date(Web):30 Jan 2015
DOI:10.1039/C4TB02130D
Transferrin (Trf)-functionalized copper nanoclusters (Trf-Cu NCs) were fabricated as a novel red-emitting fluorescent probe for the targeted bioimaging of cancer cells. A one-pot approach was developed to prepare stable, water-soluble and red-emitting Trf-Cu NCs at room temperature via a biomineralization process with Trf as the template and ascorbic acid as a green reducing agent. Trf acted not only as a stabilizer and reducer, but also as a functional ligand for targeting the transferrin receptor. The as-prepared Trf-Cu NCs showed an intense red fluorescence with a red emission peak at 670 nm (quantum yield about 6.2%), suggesting that the probe could potentially be used for bioimaging in vivo. The developed Trf-Cu NCs had excellent photostability and water solubility and exhibited a high specificity to transferrin receptor with negligible cytotoxicity. The probe was successfully applied to the targeted bioimaging of HeLa cells.
Co-reporter:Ting-Ting Sun, Ming Wu, Xi-Wen He, Wen-You Li and Xi-Zeng Feng
Journal of Materials Chemistry A 2015 vol. 3(Issue 34) pp:6971-6978
Publication Date(Web):04 Aug 2015
DOI:10.1039/C5TB01209K
In the past two decades, Cu-doped inorganic semiconductors with near-infrared (NIR) emitting have garnered stupendous research interest. Nevertheless, the incompatibility between the NIR emitting and high photoluminescence quantum yield (PLQY) of the Cu-doped fluorescent probes restricted the extensive application in biological imaging. Herein, the water soluble Cu+ doped CdS quantum dots (Cu+:CdS QDs) were prepared by using a one step synthesis method in a N2 atmosphere. The d-dots possessed an ultra small size (∼5 nm), a high QY (25.6%), NIR emission (∼700 nm) and a low cytotoxicity because of which they were used as fluorescence probes. Besides, the study of the Cu d state and the mechanism of emission proposed the explanation for the fluorescence enhancement compared with previous reports. Moreover, the optimal conditions of dopants, stabilizers, sulfur ion concentration, pH, heating time and reflux temperature were also studied systematically to acquire best-quality Cu-doped nanocrystals. Due to the excellent optical properties and favourable biocompatibility, the Cu+:CdS QDs as fluorescence probes were successfully applied to label living 3T3 cells.
Co-reporter:Ye-Yun Zhang, Xi-Wen He and Wen-You Li
RSC Advances 2015 vol. 5(Issue 87) pp:71030-71034
Publication Date(Web):14 Aug 2015
DOI:10.1039/C5RA11217F
In this present study, carbon dots (CDs) with strong fluorescence were introduced into poly(N-isopropylacrylamide) (PNIPAM) hydrogel (CDs/PNIPAM) in one pot at room temperature by atom transfer radical polymerization (ATRP). The method was simple, facile, but highly efficient and versatile. The obtained CDs/PNIPAM hybrid hydrogel was thought to combine through hydrogen bond assisted with spatial network embedding. Compared with the original CDs solution, the CDs/PNIPAM hybrid hydrogel showed temperature-sensitivity as well as strong fluorescence with a LCST of 33 °C. Around the LCST, a slight change of temperature affected the fluorescent intensity dramatically. For example, when the temperature increased from 32 °C to 33 °C, the fluorescence intensity of CDs/PNIPAM dropped sharply with a ratio of F32 to F33 as high as 3.5. Moreover, the fluorescence intensity recovered when the temperature fell. Through heating and cooling cycles, the fluorescence off–on phenomenon of the CDs/PNIPAM hybrid hydrogel was reversible and repeatable around the LCST region.
Co-reporter:Yan-Qin Wang, Ye-Yun Zhang, Xiao-Gang Wu, Xi-Wen He, Wen-You Li
Materials Letters 2015 Volume 143() pp:326-329
Publication Date(Web):15 March 2015
DOI:10.1016/j.matlet.2014.12.132
•A facile route for in situ synthesis of the Au/PNIPAM thermosensitive gels at room temperature.•The fluorescence of the Au/PNIPAM gels exhibited excellent thermosensitive properties.•The Au/PNIPAM thermosensitive gels could be developed as a temperature sensor.A facile route for in situ synthesis of the highly fluorescent Au/Poly(N-isopropylacrylamide) (Au/PNIPAM) thermosensitive gels at room temperature has been developed. The as-prepared hybrid Au/PNIPAM gels were characterized by UV–vis absorption spectroscopy, fluorescence spectroscopy, differential scanning calorimetry (DSC) measurement, thermogravimetric analysis (TGA), etc. The fluorescence intensity of the Au/PNIPAM gels exhibited excellent thermosensitive properties. Moreover, the fluorescence quenching and enhancement process was fully reversible after repeated heating and cooling cycles. So the Au/PNIPAM thermosensitive gels could be developed as fluorescence intensity variation-based temperature sensors.
Co-reporter:Dong-Yan Li, Ya-Ping Qin, Hong-Yu Li, Xi-Wen He, Wen-You Li, Yu-Kui Zhang
Biosensors and Bioelectronics 2015 Volume 66() pp:224-230
Publication Date(Web):15 April 2015
DOI:10.1016/j.bios.2014.11.023
•A “turn-on” fluorescent molecularly imprinted polymer (CdTe/SiO2/MIP) receptor was developed for detecting tyrosine phosphopeptide.•The CdTe/SiO2/MIP receptor was fabricated by the surface imprinting procedure and the epitope approach.•The receptor combined the merits of high selectivity of molecular imprinting technique and good sensitivity of CdTe QDs.•The receptor was applied to detect tyrosine phosphopeptide in the real sample.A new strategy for the manufacture of a turn-on fluorescent molecularly imprinted polymer (CdTe/SiO2/MIP) receptor for detecting tyrosine phosphopeptide (pTyr peptide) was proposed. The receptor was prepared by the surface imprinting procedure and the epitope approach with silica-capped CdTe quantum dots (QDs) as core substrate and fluorescent signal, phenylphosphonic acid (PPA) as the dummy template, 1-[3-(trimethoxysilyl) propyl] urea as the functional monomer, and octyltrimethoxysilane as the cross-linker. The synthetic CdTe/SiO2/MIP was able to selectively capture the template PPA and corresponding target pTyr peptide with fluorescence enhancement via the special interaction between them and the recognition cavities. The receptor exhibited the linear fluorescence enhancement to pTyr peptide in the range of 0.5–35 μM, and the detection limit was 0.37 μM. The precision for five replicate detections of pTyr peptide at 20 μM was 2.60% (relative standard deviation). Combining the fluorescence property of the CdTe QDs with the merits of the surface imprinting technique and the epitope approach, the receptor not only owned high recognition site accessibility and good binding affinities for target pTyr peptide, but also improved the fluorescence selectivity of the CdTe QDs, as well revealed the feasibility of fabrication of a turn-on fluorescence probe using the surface imprinting procedure and the epitope approach.
Co-reporter:Xiao-Li Zhao, Dong-Yan Li, Xi-Wen He, Wen-You Li and Yu-Kui Zhang
Journal of Materials Chemistry A 2014 vol. 2(Issue 43) pp:7575-7582
Publication Date(Web):15 Sep 2014
DOI:10.1039/C4TB01381F
In this study, we reported an epitope imprinting method on the surface of core–shell magnetic nanoparticles (NPs) for the recognition of target bovine serum album (BSA). The epitope was selected as the template molecule from the nonapeptide of surface-exposed C-terminus of BSA. The core–shell magnetic epitope molecularly imprinted polymers (Fe3O4@EMIPs) exhibited a specific capture activity for the corresponding target protein, BSA. The magnetic NPs made it easy to separate the imprinted material from solution by an external magnetic field, and the thin imprinted layer presented fast kinetics for the rebinding of the target protein. Moreover, the Fe3O4@EMIPs could separate BSA from the bovine blood sample. The epitope imprinting approach combined with magnetic NPs provided an easy and fast method for the specific recognition of BSA.
Co-reporter:Fei Zhang, Ting-Ting Sun, Yan Zhang, Qiong Li, Chao Chai, Li Lu, Wen Shen, Jun Yang, Xi-Wen He, Yu-Kui Zhang and Wen-You Li
Journal of Materials Chemistry A 2014 vol. 2(Issue 41) pp:7201-7209
Publication Date(Web):22 Aug 2014
DOI:10.1039/C4TB00920G
Magnetic quantum dots (MQDs) are an important class of agents for fluorescence (FL)/magnetic resonance (MR) dual-modal imaging due to their excellent optical and magnetic properties. However, functional MQDs prepared by a simple room-temperature route as FL/MR dual-modal imaging probes are lacking. Herein, we report the fabrication of Gd-doped CdTe quantum dots (Gd:CdTe QDs) as an agent for FL/MR dual-modality imaging. The as-designed QDs with an ultrasmall particle size are synthesized by a facile one-pot aqueous synthesis approach at room temperature. They emit strong fluorescence at 640 nm with a quantum yield of 37% in water, and they have a high longitudinal relaxation rate (r1) value of 3.27 mM−1 s−1. With the further conjugation of folic acid, the Gd:CdTe QDs can successfully label live HepG2 cells for targeted cellular imaging and present no evidence of cellular toxicity up to the concentration of 0.5 mg mL−1. They have been employed as a suitable contrast agent successfully for tumor-targeted FL/MR dual-modal imaging in a mouse model.
Co-reporter:Fei Zhang;Fei He;Xi-Wen He;Yu-Kui Zhang
Luminescence 2014 Volume 29( Issue 8) pp:1059-1065
Publication Date(Web):
DOI:10.1002/bio.2660
ABSTRACT
Mn2+-doped CdTe quantum dots (QDs) were synthesized directly via a facile surface doping strategy in aqueous solution. The best optical property emerged when the added amount of Mn2+ was 5% compared to Cd2+ in the CdTe nanoparticles and the reaction temperature was 60 °C. The fluorescence and magnetic properties of the QDs were studied. The as-prepared Mn2+-doped CdTe QDs have high quantum yield (48.13%) and a narrow distribution with an average diameter of 3.7 nm. The utility of biological imaging was also studied. Depending on the high quantum yield, cells in culture were illuminated and made more distinct from each other compared to results obtained with normal QDs. They also have a prominent longitudinal relaxivity value (r1 = 4.2 mM−1s−1), which could indicate that the Mn2+-doped CdTe QDs can be used as a potential multimodal agent for fluorescence and magnetic resonance imaging. Copyright © 2014 John Wiley & Sons, Ltd.
Co-reporter:Ya-Qiong Yang, Xi-Wen He, Yi-Zhi Wang, Wen-You Li, Yu-Kui Zhang
Biosensors and Bioelectronics 2014 Volume 54() pp:266-272
Publication Date(Web):15 April 2014
DOI:10.1016/j.bios.2013.11.004
•A novel strategy for preparing EMIP-coated CdTe quantum dots using a combination of epitope and surface imprinting approach was developed.•The prepared EMIP-coated QDs can also discriminate even one mismatched sequences from the original sequences of the epitope of the BSA.•Compared with directly using BSA as the template, the imprinting factor and adsorption capacity of EMIP-coated QDs were greatly increased.•This approach was applied to determine and separate BSA from real samples.A novel epitope molecularly imprinted polymer (EMIP) for specific recognition and direct fluorescent quantification of the target protein bovine serum albumin (BSA) was demonstrated where polymerization was performed on the surface of silica nanospheres embedded CdTe quantum dots (QDs). The synthetic peptide derived from the surface-exposed C-terminus of bovine serum albumin (BSA, residues 599-607) was selected as the template molecule. The resulting EMIP film was able to selectively capture the template peptide and the corresponding target protein BSA via the recognition cavities. Based on the fluorescence quenching, the EMIP-coated QDs (molecular imprinted polymer coating CdTe QDs using epitope as the template) nanospheres were successfully applied to the direct fluorescence quantification of BSA. Compared with BMIP-coated QDs (molecular imprinted polymer coating CdTe QDs using BSA as the template), the imprinting factor and adsorption capacity of EMIP-coated QDs were greatly increased. The prepared EMIP-coated QDs can also discriminate even one mismatched sequences from the original sequences of the epitope of the BSA. The practical analytical performance of the EMIP-coated QDs was examined by evaluating the detection of BSA in the bovine calf serum sample with satisfactory results. In addition, the resulting EMIP-coated QDs nanospheres were also successfully applied to separating BSA from the bovine blood sample.
Co-reporter:Yan-Qin Wang, Tong Zhao, Xi-Wen He, Wen-You Li, Yu-Kui Zhang
Biosensors and Bioelectronics 2014 Volume 51() pp:40-46
Publication Date(Web):15 January 2014
DOI:10.1016/j.bios.2013.07.028
•A novel core-satellite CdTe/Silica/Au NCs hybrid sphere was successfully fabricated.•The hybrid spheres have been developed as a ratiometric fluorescence probe.•The ratiometric fluorescent probe was applied in the determination of Cu2+ in vegetable samples.Herein, we synthesized a novel core-satellite CdTe/Silica/Au NCs hybrid sphere by covalently linking the separately synthesized highly fluorescent bovine serum albumin (BSA) stabilized gold nanoclusters (Au@BSA NCs) to the surface of the amino functionalized CdTe@SiO2 spheres by using the EDC chemistry. Numerous “satellites” of Au NCs were linked on the surface of the CdTe@SiO2 by the way of amide bonding. The synthesized dual-emission hybrid spheres were further characterized by the transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), UV–vis absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy, photoluminescence (PL), etc. Finally, the CdTe/Silica/Au NCs hybrid spheres were developed as ratiometric fluorescence probe for the determination of Cu2+ with high sensitivity and selectivity. The fluorescence intensity ratio (F545 nm/F655 nm) of the probe against the concentration of Cu2+ showed a good linear relationship from 6.0×10−7 mol L−1 to 100.0×10−7 mol L−1. It showed an excellent reproducibility (0.67% relative standard deviation for 10 replicate measurements of Cu2+ at 40.0×10−7 mol L−1) and low detection limit (4.1×10−7 mol L−1). Furthermore, the ratiometric fluorescent probe was successfully applied in the determination of Cu2+ in vegetable samples with satisfactory results.
Co-reporter:Yan-Qin Wang, Xi-Wen He, Wen-You Li and Yu-Kui Zhang
Journal of Materials Chemistry A 2013 vol. 1(Issue 11) pp:2202-2208
Publication Date(Web):22 Jan 2013
DOI:10.1039/C3TC00681F
We fabricated QD–silica–Au NC hybrid spheres, in which the solid silica core contained QDs while the mesostructured silica shell contained Au NCs, by a two-step synthesis procedure. The hybrid spheres were further characterized by high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and nitrogen adsorption–desorption analysis to confirm the formation of the ternary hybrid structure. The as-prepared ternary hybrid spheres showed an interesting fluorescence spectrum variation and further could be developed as a precursor for fabricating multicolor fluorescence bar codes by using L-cysteine (L-Cys) as an effective post-encoding adjuster. A small variation of the concentration of L-Cys led to a prominent change of the precursor's fluorescence intensity ratio, which could correspond to a series of distinguishable multicolor fluorescent bar codes. Furthermore, the multicolour fluorescence bar codes fabricated by the post-encoding method showed excellent non-reversibility, batch-to-batch reproducibility of the intensity ratios, photophysical and thermal stability properties and anti-interference capabilities, which are important virtues for them to be used in high-throughput bio-labelling and imaging.
Co-reporter:Wei Zhang, Xi-Wen He, Ya-Qiong Yang, Wen-You Li and Yu-Kui Zhang
Journal of Materials Chemistry A 2013 vol. 1(Issue 3) pp:347-352
Publication Date(Web):17 Oct 2012
DOI:10.1039/C2TB00022A
In this work, aminophenylboronic acid functionalized mesoporous silica coated CdTe quantum dots (APBA-coated QDs) were synthesized and applied to the selective capture and fluorescent quantification of glycoproteins. The as-prepared APBA-coated QDs, relying on the interaction between APBA and cis-diol containing structures, demonstrated excellent selectivity for the glycoproteins. Their high surface area and APBA-enriched silica matrixes give rise to faster binding kinetics and higher binding capacity for the glycoproteins, which further make them attractive for biomedical/chemical sensing applications. Based on the fluorescent properties of the particles, the as-prepared APBA-coated QDs were successfully applied to the fluorescence quantification of glycoproteins. The present study provides a facile strategy to fabricate functionalized fluorescent materials and is of great significance for isolation and detection of glycoproteins in proteomics.
Co-reporter:Dong-Yan Li, Xi-Wen He, Yang Chen, Wen-You Li, and Yu-Kui Zhang
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 23) pp:12609
Publication Date(Web):November 20, 2013
DOI:10.1021/am403942y
This work presented a novel strategy for the synthesis of the hybrid structure silica/CdTe/molecularly imprinted polymer (Si-NP/CdTe/MIP) to recognize and detect the template bovine hemoglobin (BHb). First, amino-functionalized silica nanoparticles (Si-NP) and carboxyl-terminated CdTe quantum dots (QDs) were assembled into composite nanoparticles (Si-NP/CdTe) using the EDC (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride) chemistry. Next, Si-NP/CdTe/MIP was synthesized by anchoring molecularly imprinted polymer (MIP) layer on the surface of Si-NP/CdTe through the sol–gel technique and surface imprinting technique. The hybrid structure possessed the selectivity of molecular imprinting technique and the sensitivity of CdTe QDs as well as well-defined morphology. The binding experiment and fluorescence method demonstrated its special recognition performance toward the template BHb. Under the optimized conditions, the fluorescence intensity of the Si-NP/CdTe/MIP decreased linearly with the increase of BHb in the concentration range 0.02–2.1 μM, and the detection limit was 9.4 nM. Moreover, the reusability and reproducibility and the successful applications in practical samples indicated the synthesis of Si-NP/CdTe/MIP provided an alternative solution for special recognition and determination of protein from real samples.Keywords: fluorescent detection; molecularly imprinted polymer; protein recognition; quantum dots;
Co-reporter:Yang Chen;Xi-Wen He;Jie Mao;Yu-Kui Zhang
Journal of Separation Science 2013 Volume 36( Issue 20) pp:3449-3456
Publication Date(Web):
DOI:10.1002/jssc.201300709
Protein-imprinted polymers with hollow cores that have a super-high imprinting factor were prepared by etching the core of the surface-imprinted polymers that used silica particles as the support. Lysozyme as template was modified onto the surface of silica particles by a covalent method, and after polymerization and the removal of template molecules, channels through the polymer layer were formed, which allowed a single-protein molecule to come into the hollow core and attach to the binding sites inside the polymer layer. The adsorption experiments demonstrated that the hollow imprinted polymers had an extremely high binding capacity and selectivity, and thus a super-high imprinting factor was obtained. The as-prepared imprinted polymers were used to separate the template lysozyme from egg white successfully, indicating its high selectivity and potential application in the field of separation of protein from real samples.
Co-reporter:Feng-Xian Gao, Xiao-Li Zhao, Xi-Wen He, Wen-You Li and Yu-Kui Zhang
Analytical Methods 2013 vol. 5(Issue 23) pp:6700-6708
Publication Date(Web):19 Sep 2013
DOI:10.1039/C3AY41069B
A pH and temperature dual-responsive macroporous protein imprinted cryogel was synthesized by a facile “one-pot” method using N-isopropylacrylamide (NIPAAm) and 4-vinylphenylboronic acid (p-VPBA) as the main functional monomers. The smart molecularly imprinted polymers (MIPs) could recognize the target glycoprotein (ovalbumin (OB) as a template) dynamically and reversibly. The morphologies and features of the cryogels were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The rebinding and swelling experiments showed that the MIP cryogels could respond quickly to temperature and pH. Various parameters such as the pH value of the protein solution, adsorption temperature, and the rebinding time were optimized. Under the optimal conditions, a higher adsorption capacity and imprinting factor of the MIP cryogel were achieved, and were found to be 21 mg g−1 and 3.4, respectively. Moreover, the MIP cryogel exhibited good selectivity and acceptable regeneration capacity. A real sample analysis further demonstrated its feasibility for the target protein separation. These excellent performances suggested that the obtained imprinted cryogel should be a promising candidate for recognition and separation of OB.
Co-reporter:Ye-Yun Zhang, Ming Wu, Yan-Qin Wang, Xi-Wen He, Wen-You Li, Xi-Zeng Feng
Talanta 2013 Volume 117() pp:196-202
Publication Date(Web):15 December 2013
DOI:10.1016/j.talanta.2013.09.003
•Strong fluorescent carbon dots with excellent quality have been synthesized by hydrothermally refluxing lactose and tris(hydroxymethyl) aminomethane (i.e. Tris).•This facile approach was simple, mild, green and allows large-scale production of CDs without any post-treatment.•The CDs were applied to optical bioimaging of HeLa cells, showing low cytotoxicity and excellent biocompatibility.Due to their unique optical and biochemical properties, the water-soluble fluorescent carbon dots (CDs) have attracted a lot of attention recently. Here, strong fluorescent carbon dots with excellent quality have been synthesized by the hydrothermal refluxing method using lactose as carbon source and tris(hydroxymethyl) aminomethane (i.e. Tris) as surface passivation reagent. This facile approach was simple, efficient, economical, green without pollution, and allows large-scale production of CDs without any post-treatment. TEM measurements showed that the resulting particles exhibited an average diameter of 1.5 nm. The obtained CDs possess small particle sizes, good stability in a wide range of pH values (pH 3.5–9.5), high tolerance of salt concentration, strong resistibility to photobleaching, and a fluorescent quantum yield up to 12.5%. The CDs were applied to optical bioimaging of HeLa cells, showing low cytotoxicity and excellent biocompatibility.Strong fluorescent carbon dots with excellent quality were synthesized by a single-step hydrothermal refluxing method using lactose and tris(hydroxymethyl) aminomethane.
Co-reporter:Feng-Xian Gao, Xiao-Tong Ma, Xi-Wen He, Wen-You Li, Yu-Kui Zhang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2013 Volume 433() pp:191-199
Publication Date(Web):20 September 2013
DOI:10.1016/j.colsurfa.2013.05.018
•Surface imprinting nanosphere was prepared using covalent template immobilization.•The imprinted nanospheres could rebind the template glycoprotein.•The rebinding affinity of the imprinted nanospheres was thermo- and pH-dependent.•High adsorption, fast rebinding kinetics, excellent selectivity and reusability.•The applicability was favorable in a real sample analysis.Through covalent immobilization of template and surface imprinting, smart molecularly imprinted polymer nanospheres were developed for selective separation of the glycoprotein ovalbumin (OB). First, a boronic acid group-bearing poly (methyl methacrylate) (b-PMMA) nanosphere was synthesized directly at the high temperature of 70 °C. The b-PMMA nanosphere could pre-immobilize the template OB on its surface by forming reversible covalent bonds. Then the precipitation polymerization of N-isopropylacrylamide (NIPAAm) and acrylamide (AAm) readily occurred on the b-PMMA nanosphere as a core at room temperature, leading to the formation of core–shell molecular imprinting nanosphere. The experiments showed the rebinding affinity of the imprinted nanospheres was thermo- and pH-dependent. The resulting imprinted nanospheres showed high adsorption capacity and good specific recognition behavior toward the template molecule, and no obvious reusability deterioration was observed. Most notably, the imprinted nanospheres reached saturated adsorption within 20 min, indicating faster rebinding kinetics. In addition, the imprinted nanospheres were successfully applied to selectively separate the target OB from an egg white sample.
Co-reporter:Fei Zhang, Xi-Wen He, Wen-You Li and Yu-Kui Zhang
Journal of Materials Chemistry A 2012 vol. 22(Issue 41) pp:22250-22257
Publication Date(Web):04 Sep 2012
DOI:10.1039/C2JM33560C
In the last two decades, near-infrared (NIR) emitting Cu-doped quantum dots (QDs) have stimulated stupendous research interest for their excellent optical properties. Due to the synthetic method in the organic phase, almost none of the NIR emitting Cu-doped QDs were used as the fluorescent probes for biological imaging, despite being employed for applications in many fields. In this work, we successfully synthesized water-soluble Cu-doped CdS quantum dots (Cu:CdS d-dots) with an emission wavelength at 722 nm using a fast and facile hydrothermal method. The optical properties of the d-dots and several key parameters of the synthesis conditions such as dopant concentration, reaction temperature, reflux time, and especially the pH of the reaction mixture were systematically studied, and the mechanism of these parameters is also discussed. A red shift of the emission maximum as a consequence of the increased reaction temperature was observed, but it does not move to the NIR region until Cu2+ is doped even at the highest reflux temperature in aqueous solution. The d-dots have good water solubility and biocompatibility for successful labeling the living HeLa cells as fluorescence probe.
Co-reporter:Wei Zhang, Xi-Wen He, Wen-You Li and Yu-Kui Zhang
Chemical Communications 2012 vol. 48(Issue 12) pp:1757-1759
Publication Date(Web):07 Dec 2011
DOI:10.1039/C2CC17200C
A thermo-sensitive imprinted polymer coating CdTe quantum dots was developed to prepare fluorescent thermo-sensitive protein-affinity materials, which exhibited high specific recognition ability towards target proteins.
Co-reporter:Yan-Qin Wang, Yang Liu, Xi-Wen He, Wen-You Li, Yu-Kui Zhang
Talanta 2012 Volume 99() pp:69-74
Publication Date(Web):15 September 2012
DOI:10.1016/j.talanta.2012.04.064
Chemically denatured ovalbumin (dOB) was used to modify the surface of 3-mercaptopropionic acid (MPA) stabilized CdTe quantum dots (QDs), which resulted in a great enhancement of the synchronous fluorescence intensity. Moreover, dOB shell layer can effectively prevent the binding of other cations onto the QDs core and enhance the selective binding ability of Hg2+ to dOB coated CdTe QDs (CdTe-dOB QDs). A simple method with high sensitivity and selectivity was developed for the determination of Hg2+ with the CdTe-dOB QDs as fluorescence probe based on the merits of synchronous fluorescence spectroscopy (SFS). When scanning with excitation and emission wavelengths of 250 nm and 470 nm (Δλ=λem−λex=220 nm), respectively, the maximum synchronous fluorescence peak of the CdTe-dOB QDs was located at 328 nm. Under optimal conditions, the change of the synchronous fluorescence intensity was in good linear relationship with the Hg2+ concentration in the range of 0.08×10−7 to 30.0×10−7 mol L−1 and the detection limit was 4.2×10−9 mol L−1 (S/N=3). The relative standard deviation of seven replicate measurements for the concentration of 2.0×10−7 mol L−1 and 20.0×10−7 mol L−1 were 2.8% and 2.3%, respectively. Compared with general fluorescence methods, the proposed method, which combined the advantages of high sensitivity of synchronous fluorescence and specific response of Hg2+ to CdTe-dOB, had a wider linear range and higher sensitivity. Furthermore, the proposed method was applied to the determination of trace Hg2+ in water samples with satisfactory results.Highlights► As-prepared CdTe-dOB QDs showed a specific response for the Hg2+ determination. ► Detection limit of the probe for Hg2+ determination was 4.2×10−9 mol L−1. ► Satisfactory results were obtained from the water samples.
Co-reporter:Wei Zhang, Xi-Wen He, Yang Chen, Wen-You Li, Yu-Kui Zhang
Biosensors and Bioelectronics 2012 Volume 31(Issue 1) pp:84-89
Publication Date(Web):15 January 2012
DOI:10.1016/j.bios.2011.09.042
A new type of molecularly imprinted polymer (MIP)-based fluorescent artificial receptor was developed by anchoring MIP on the surface of denatured bovine serum albumin (dBSA) modified CdTe quantum dots (QDs) using the surface molecular imprinting process. The approach combined the merits of molecular imprinting technology and the fluorescent property of the CdTe QDs. The dBSA was used not only to modify the surface defects of the CdTe QDs, but also as assistant monomer to create effective recognition sites. Three different proteins, namely lysozyme (Lyz), cytochrome c (Cyt) and methylated bovine serum albumin (mBSA), were tested as the template molecules and then the receptors were synthesized by sol–gel reaction (imprinting process). The results of fluorescence and binding experiments demonstrated the recognition performance of the receptors toward the corresponding template. Under optimum conditions, the linear range for Lyz was from 1.4 × 10−8 to 8.5 × 10−6 M, and the detection limit was 6.8 nM. Moreover, the new artificial receptors were applied to separate and detect Lyz in real samples. This fluorescent artificial receptor may serve as a starting point in the design of highly effective synthetic fluorescent receptor for recognition of target protein.Highlights► We developed a MIP-coated QDs receptor for protein recognition. ► The dBSA was used to modify the surface of the QDs. ► The results of fluorescence test demonstrated the performance of the receptor. ► Binding test further exhibited the recognition ability of the receptor. ► The receptor was applied to separate and detect Lyz in real samples.
Co-reporter:Yan-Qin Wang, Ye-Yun Zhang, Fei Zhang and Wen-You Li
Journal of Materials Chemistry A 2011 vol. 21(Issue 18) pp:6556-6562
Publication Date(Web):25 Mar 2011
DOI:10.1039/C1JM10104H
In the present study, for the first time, without the help of any amphiphilic polymers or polymerizable surfactants, 3-mercaptopropionic acid (MPA) capped CdTe quantum dots (QDs) could be one-pot copolymerized into poly(N-isopropylacrylamide) (PNIPAM) microspheres during the monomer polymerization process just by controlling the synthesis temperature at two different polymerization stages. In the first stage, NIPAM monomers were initiated by potassium persulfate (KPS) below the lower critical solution temperature (LCST) to form PNIPAM networks with CdTe QDs distributed throughout. In the second stage, when the polymerize temperature was raised above the LCST, the PNIPAM networks collapsed to form spheres and the CdTe QDs were entrapped into the PNIPAM microspheres (denoted as CdTe–PNIPAM microspheres). Transmission electron microscopy (TEM) images showed that CdTe QDs have been successfully entrapped within the PNIPAM matrix. According to the dynamic light scattering (DLS) results, the CdTe–PNIPAM hybrid microspheres had a significantly narrow size distribution and their mean hydrodynamic diameter was about 267 nm. Compared with the original CdTe QDs, the CdTe–PNIPAM microspheres exhibited not only a prominent red-shift of their emission wavelength (as much as 36 nm), but also temperature dependent on–off fluorescence properties. Around the LCST, when the temperature was increasing, the fluorescence intensity decreased sharply; when cooling the solution, the fluorescence intensity would restore. Moreover, after repeated heating and cooling cycles, the photoluminescence (PL) quenching and enhancement processes were fully reversible around the LCST region.
Co-reporter:Lei Qin;Xi-Wen He;Xia Yuan
Analytical and Bioanalytical Chemistry 2011 Volume 399( Issue 10) pp:3375-3385
Publication Date(Web):2011 April
DOI:10.1007/s00216-011-4736-6
A new approach is reported on the use of poly(N-isopropylacrylamide) (PNIPAM)-coated molecularly imprinted beads (coated MIP beads) for controlling the release of protein. The coated MIP beads were composed of double layers, an internal thermosensitive lysozyme-imprinted layer, and an external PNIPAM layer. The coated MIP beads were prepared by two-step surface-initiated living-radical polymerization (SIP). In this systemic study, the coated MIP beads had good selectivity to the template protein (lysozyme) and temperature stimulus-responsive behavior, both of which were superior to those of MIP beads having a layer of thermosensitive lysozyme-imprinted polymer only. Using the coated MIP beads, reference proteins and the template lysozyme could be released separately at 38 °C and at 23 °C. The corresponding coated non-imprinted beads (coated NIP beads) did not have such double thermosensitive “gates” with specific selectivity for a particular protein. The proposed smart controlled imprinted system for protein is attractive for chemical carriers, drug-delivery system, and sensors.
Co-reporter:Dr. Lei Qin; Xi-Wen He;Man Jia; Wen-You Li; Yu-Kui Zhang
Chemistry - A European Journal 2011 Volume 17( Issue 5) pp:1696-1704
Publication Date(Web):
DOI:10.1002/chem.201000875
Abstract
The main objective of this study was to develop a new methodology for the preparation of a protein (antigen) that is a molecularly imprinted polymer (MIP, an artificial antibody) modified onto the surface of a silica skeleton in which the resulting stationary phase is thermosensitive. The silica monolithic skeleton with vinyl groups was synthesized in a stainless-steel column by using a mild one-step sol–gel process with two types of precursor: methyltrimethoxysilane (MTMS) and γ-methacryloxypropyltrimethoxysilane (γ-MAPS). Subsequently, three types of the thermosensitive protein MIP were anchored onto the surface of the silica skeleton to prepare the MIP monoliths, which were systematically investigated for back pressure and separation ability at different temperatures to establish good imprinting conditions. Under the optimized imprinting conditions, the chromatographic behavior of the thermosensitive MIP monolith exhibited strong retention ability for the lysozyme template (target antigen) in relation to the nonimprinting monolith (NIP monolith). The imprinting factor (IF) for lysozyme reached 3.48 at 20 °C. Moreover, this new type of artificial antibody displayed favorable binding characteristics for lysozyme over competitive proteins and was further evaluated to selectively separate lysozyme in a real sample by using an on-line method. The run-to-run and column-to-column repeatability measurements of the thermosensitive MIP monoliths were also satisfactory.
Co-reporter:Run-Run Chen, Lei Qin, Man Jia, Xi-Wen He, Wen-You Li
Journal of Membrane Science 2010 Volume 363(1–2) pp:212-220
Publication Date(Web):1 November 2010
DOI:10.1016/j.memsci.2010.07.026
A novel and efficient molecularly imprinted membrane (MIM) for the selective transport and separation of lysozyme was synthesized by the molecular imprinting technique. The layer of molecularly imprinted materials containing recognition sites for the lysozyme was formed on the poly(acrylontrile-co-N,N′-diethylaminodithiocarbamoylmethylstyrene) [P(AN-co-DTCS)] membrane, which was prepared via a phase inversion method and modified with photosensitive dithiocarbamate group for surface initiated living-radical polymerization. Thus obtained MIM was characterized and evaluated by Fourier transform infrared spectroscopy, scanning electron microscopy and competitive transport studies. Under the optimum conditions, the transporting factor of the lysozyme reached 2.41 when the time of permeation was 24 h. The separation of the mixture of lysozyme and bovine hemoglobin and the mixture of lysozyme and cytochrome c showed that the selectivity factor (β) reached 2.51 and 2.13, respectively. All these results indicated that the excellent selectivity separation performance of the MIM for lysozyme arose from the size and structure of the imprinted sites on the MIM, which offered great potential for separation and purification in commercial applications.Research highlights▶ A novel molecularly imprinted membrane (MIM) for the selective transport and separation of lysozyme was synthesized by the molecular imprinting technique. ▶ The layer of molecularly imprinted materials containing recognition sites for the lysozyme was formed on the poly(acrylontrile-co-N,N′-diethylaminodithiocarbamoylmethylstyrene) membrane, which was prepared via a phase inversion method and modified with photosensitive dithiocarbamate group for surface initiated living-radical polymerization. ▶ This molecular imprinting approach provided promising tool for the protein separation.
Co-reporter:Wei Zhang, Lei Qin, Run-Run Chen, Xi-Wen He, Wen-You Li, Yu-Kui Zhang
Applied Surface Science 2010 Volume 256(Issue 9) pp:3000-3005
Publication Date(Web):15 February 2010
DOI:10.1016/j.apsusc.2009.11.064
Abstract
A novel protein imprinted polymer was prepared using acryloyl-β-cyclodextrin (β-CD) and acrylamide as monomers on the surface of silica gel. The bovine hemoglobin was used as template and β-CD was allowed to self-assemble with the template protein through hydrogen bonding and hydrophobic interaction. Polymerization was carried out in the presence of acrylamide as an assistant monomer, which resulted in a novel protein imprinted polymer. After removing the template, imprinted cavities with the shape and spatial distribution of functional groups were formed. Bovine serum albumin (BSA) cytochrome c (Cyt) and lysozyme (Lyz) were employed as non-template proteins to test the imprinting effect and the specific binding of bovine hemoglobin to the polymer. The results of the adsorption experiments indicated that such protein imprinted polymer, which was synthesized with β-CD and acrylamide as monomers, could selectively recognize the template protein.
Co-reporter:Lei Qin, Xi-Wen He, Wei Zhang, Wen-You Li and Yu-Kui Zhang
Analytical Chemistry 2009 Volume 81(Issue 17) pp:7206
Publication Date(Web):August 5, 2009
DOI:10.1021/ac900676t
A thermosensitive macroporous hydrogel showing selectivity for the lysozyme was developed by an imprinting procedure that is based on metal coordinate interaction. A metal chelate monomer [N-(4-vinyl)-benzyl iminodiacetic acid] forming coordination complex with the template protein in the presence of Cu ions co-polymerized with N-isopropylacrylamide and acrylamide, using N,N-methylenebisacrylamide as the cross-linker to prepare the thermosensitive protein-imprinted hydrogel. The synergetic combination of the smart property of the macroporous thermosensitive hydrogel with the merits of the coordinate interaction improved the selectivity and adsorption capacity, with respect to template lysozyme. The macropores were created by the frozen polymerization, and the influences of frozen polymerization and the chelate monomer content on the hydrogel affinity were investigated. The imprinted hydrogel can respond not only to external stimuli, but also to the template protein with a certain degree of shrinking. In recognition of the protein, the interaction of the imprinted thermosensitive hydrogel to the protein can be switched between the coordinate effect and the electrostatic effect by adding or not adding Cu ions. Finally, this imprinted hydrogel was used to purify the template lysozyme from the mixture of proteins and the real sample, which demonstrated its high selectivity.
Co-reporter:Lei Qin, Xi-Wen He, Wei Zhang, Wen-You Li, Yu-Kui Zhang
Journal of Chromatography A 2009 Volume 1216(Issue 5) pp:807-814
Publication Date(Web):30 January 2009
DOI:10.1016/j.chroma.2008.12.007
A new and facile fabricating method for lysozyme molecularly imprinted polymer beads (lysozyme-MIP beads) in aqueous media was presented. Mesoporous chloromethylated polystyrene beads (MCP beads) containing dithiocarbamate iniferter (initiator transfer agent terminator) were used as supports for the grafting of lysozyme imprinted copolymers with acrylamide and N,N′-methylenebisacrylamide through surface initiated living-radical polymerization (SIP). After the polymerization, a layer of lysozyme-MIP was formed on the MCP beads. The SIP allowed an efficient control of the grafting process and suppressed solution propagation. Therefore, the obtained lysozyme-MIP beads had a large quantity of well-distributed pores on the surface without any visible gel formation in solution and were more advantageous comparing with traditional MIPs which were prepared by traditionally initiated radical polymerization. The obtained composites were characterized by Fourier transform infrared spectroscopy, elemental analysis, nitrogen sorption analysis and scanning electron microscopy. Chromatographic behaviors of the column packed with lysozyme-MIP beads exhibited ability in separating lysozyme from competitive protein (bovine hemoglobin, bovine serum albumin, ovalbumin or cytochrome c) in aqueous mobile phase.
Co-reporter:Wei Zhang, Lei Qin, Xi-Wen He, Wen-You Li, Yu-Kui Zhang
Journal of Chromatography A 2009 Volume 1216(Issue 21) pp:4560-4567
Publication Date(Web):22 May 2009
DOI:10.1016/j.chroma.2009.03.056
A novel protein imprinted polymer for selective recognition of lysozyme was obtained. Acryloyl-β-cyclodextrin, which offered hydrophilic exterior and hydrophobic cavity that were allowed to self-assemble with the template protein through hydrogen interaction and hydrophobic interaction, was synthesized and used as the functional monomer. Polymerization was carried out in the presence of acrylamide as an assistant monomer, which resulted in a new type of protein imprinted polymer. Langmuir adsorption model was employed to describe the isotherms, and maximum adsorption capacity was evaluated. The performance of such imprinted polymer was further demonstrated by high-performance liquid chromatography, and the results showed that the column packed with the lysozyme imprinted silica beads could effectively separate lysozyme from the mixture of lysozyme–cytochrome c, lysozyme–bovine serum albumin, lysozyme–avidin or lysozyme–methylated bovine serum albumin, which showed its high selectivity.
Co-reporter:Fang Mei;Xi-Wen He;Yu-Kui Zhang
Luminescence 2009 Volume 24( Issue 6) pp:379-385
Publication Date(Web):
DOI:10.1002/bio.1123
Abstract
In this paper, we systematically investigated the influence of graft reagents having an amino or a carboxyl terminus with different chain lengths on the fluorescence properties of water-soluble thioglycolic acid-stabilized CdTe nanocrystals (TGA–CdTe). Strong enhancement effects of the grafting on the fluorescence intensity of TGA–CdTe were observed. The experiment results demonstrated that short-chain-length grafting can increase the fluorescence intensity of CdTe nanocrystals (NCs) better than long-chain-length grafting, and the grafting did not influence the emission wavelength of the CdTe NCs. The fluorescence intensity of the carboxyl-grafted TGA–CdTe was more stable than that of the amino-grafted TGA–CdTe at wide pH ranges (pH 5.1–10.0). Copyright © 2009 John Wiley & Sons, Ltd.
Co-reporter:Lei Qin, Xi-Wen He, Wen-You Li, Yu-Kui Zhang
Journal of Chromatography A 2008 Volume 1187(1–2) pp:94-102
Publication Date(Web):11 April 2008
DOI:10.1016/j.chroma.2008.02.004
A novel molecularly imprinted polymer (MIP) selective for tryptophan (Trp) was described where polymerization was performed in aqueous media. Three kinds of molecularly imprinted polymers were prepared with surface molecular imprinting technique on functionalized silica gel (F-silica gel). MIPs prepared using bonded β-cyclodextrin (β-CD) and acrylamide (AA), either separately or in combination have shown various recognition properties. The results of adsorption experiments indicated that the selectivity of MIP, which was synthesized with bonded β-CD and AA [MIP(1)], was superior to those obtained with AA [MIP(2)] or bonded β-CD [MIP(3)]. In addition, the high-performance liquid chromatography (HPLC) column packed with MIP(1) could not only separate Trp from other aromatic amino acids, but also separate the template from its enantiomer in aqueous mobile phase. This study developed a new method for chiral amino acid separation and purification.
Co-reporter:Yun-Li Wu, Fei He, Xi-Wen He, Wen-You Li, Yu-Kui Zhang
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2008 Volume 71(Issue 4) pp:1199-1203
Publication Date(Web):15 December 2008
DOI:10.1016/j.saa.2008.03.018
Nanoparticles of cadmium telluride (CdTe) coated with thioglycolic acid (TGA) were prepared in the water phase. The interaction between CdTe nanoparticles (NPs) and lysozyme (Lyz) was investigated by fluorescence and circular dichroism (CD) spectroscopy at pH 7.40. It was proved that the fluorescence quenching of Lyz by CdTe NPs was mainly a result of the formation of CdTe–Lyz complex. By the fluorescence quenching results, the Stern–Volmer quenching constant (KSV), binding constant (Ka) and binding sites (n) were calculated. The binding distance (r) between Lyz (the donor) and CdTe NPs (the acceptor) was obtained according to fluorescence resonance energy transfer (FRET). Gradual addition of CdTe NPs to the solution of Lyz led to a marked increase in fluorescence polarization (P) of Lyz, which indicated that CdTe NPs were located in a restricted environment of Lyz. The effect of CdTe NPs on the conformation of Lyz has been analyzed by means of synchronous fluorescence spectra and CD spectra, which provided the evidence that the secondary structure of Lyz has been changed by the interaction of CdTe NPs with Lyz.
Co-reporter:Juan Li, Fang Mei, Wen-You Li, Xi-Wen He, Yu-Kui Zhang
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2008 Volume 70(Issue 4) pp:811-817
Publication Date(Web):September 2008
DOI:10.1016/j.saa.2007.09.017
The thioglycolic acid-functionalized CdTe quantum dots (QDs) were synthesized in aqueous solution using safe and low-cost inorganic salts as precursors. Fluorescence resonance energy transfer (FRET) system was constructed between CdTe QDs (donor) and butyl-rhodamine B (BRB) (acceptor) in the presence of cetyltrimethylammonium bromide (CTMAB). CTMAB micelles formed in water reduced the distance between the donor and the acceptor significantly and thus improved the FRET efficiency, which resulted in an obvious fluorescence enhancement of the acceptor. Several factors which impacted the fluorescence spectra of the FRET system were studied. The energy transfer efficiency (E) and the distance (r) between CdTe and BRB were obtained. The feasibility of the prepared FRET system as fluorescence probe for detecting Hg(II) in aqueous solution was demonstrated. At pH 6.60, a linear relationship could be established between the quenched fluorescence intensity of BRB and the concentration of Hg(II) in the range of 0.0625–2.5 μmol L−1. The limit of detection was 20.3 nmol L−1. The developed method was proved to be sensitive and repeatable to detect Hg(II) in a wide range in aqueous solutions.
Co-reporter:Fang Mei;Xi-Wen He;Yu-Kui Zhang
Journal of Fluorescence 2008 Volume 18( Issue 5) pp:883-890
Publication Date(Web):2008 September
DOI:10.1007/s10895-008-0318-1
CdHgTe nanoparticles (NPs) with the emission in the near-infrared regions were prepared in aqueous solution, and were characterized by transmission electron microscopy, X-ray diffraction spectrometry, spectrofluorometry and ultraviolet-visible spectrometry. Based on the fluorescence quenching of CdHgTe NPs in the presence of proteins, a novel method for the determination of proteins with CdHgTe NPs as a near-infrared fluorescence probe was developed. Maximum fluorescence quenching was observed with the excitation and emission wavelengths of 500 and 693 nm, respectively. Under the optimal conditions, the calibration graphs were linear in the range of 0.04 × 10−6–5.6 × 10−6 g ml−1 for lysozyme (Lyz) and 0.06 × 10−6–6.1 × 10−6 g ml−1 for bovine hemoglobin (BHb), respectively. The limits of detection were 13 ng ml−1 for Lyz and 27 ng ml−1 for BHb, respectively. Four synthetic samples were determined and the results were satisfied.
Co-reporter:Xiao-Tong Ma, Xi-Wen He, Wen-You Li, Yu-Kui Zhang
Sensors and Actuators B: Chemical (July 2017) Volume 246() pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.snb.2017.02.137
•A novel epitope molecularly imprinted polymer based quartz crystal microbalance (EMIP-QCM) sensor was established.•The simple drop-coating method involved for fabricating EMIP-QCM sensor was used for the first time.•The prepared EMIP-QCM sensor combined the selectivity of epitope imprinted polymers and sensitivity of quartz crystal microbalance sensors.•The prepared EMIP-QCM sensor could be used for real sample analysis.Quantitative determination of biomacromolecules has great significance. Quartz crystal microbalance sensors are favored by their sensibility while their selectivity was limited. Molecularly imprinted polymer has great selectivity performance. By combining the advantages of quartz crystal microbalance and molecularly imprinted polymer, this work established an epitope molecularly imprinted polymer based quartz crystal microbalance sensor. Using the epitope of human serum albumin as the template, the epitope molecularly imprinted polymer (EMIP) was successfully synthesized. Then a simple coating method was applied to fabricate the epitope molecularly imprinted polymer based quartz crystal microbalance sensor (EMIP-QCM). The EMIP-QCM sensor had good sensibility and selectivity to the target human serum albumin. The linear range was from 0.050 μg mL−1 to 0.500 μg mL−1 and the detection limit was calculated to be 0.026 μg mL−1. In addition, it could be used in real sample analysis and had good accuracy and reproducibility. This method proposed a general and simple way of establishing quartz crystal microbalance sensors for sensitive determination of biomacromolecules.An epitope molecularly imprinted polymer (EMIP) was synthesized and coated onto the quartz crystal microbalance chip (QCM) to establish a novel sensor (EMIP-QCM) for sensitive determination of target protein in real samples.Download high-res image (191KB)Download full-size image
Co-reporter:Yun-Jing Yan, Xi-Wen He, Wen-You Li, Yu-Kui Zhang
Biosensors and Bioelectronics (15 May 2017) Volume 91() pp:
Publication Date(Web):15 May 2017
DOI:10.1016/j.bios.2016.12.040
•A novel imprinted fluorescent sensor N-GQDs/SiO2/MIP was fabricated.•The introducing of metal-chelation made the template fixed more firmly.•The N-GQDs/SiO2/MIP with double templates displayed higher imprinting effect to Cyt C.•N-GQDs were introduced as a new fluorescent source.A novel fluorescent sensor nitrogen-doped graphene quantum dots (N-GQDs)/SiO2/molecular imprinting polymer（N-GQDs/SiO2/MIP）was fabricated by surface imprinting and epitope imprinting to recognize and detect the target protein cytochrome c (Cyt C) with fluorescence quenching. In the polymerization process, the C- and N-terminal nonapeptides of Cyt C were selected as the double templates which were fixed by functional monomer (zinc acrylate) through metal chelation and steady six-membered ring. The linear range of fluorescence quenching for this receptor towards Cyt C was 0.20–60 μM, and the detection limit was 0.11 μM. The precision for six times replicate determination of Cyt C at 30 μM was 1.20%, and the imprinting factor (IF) was 3.06. The recoveries of the material to Cyt C in urine were 99.3–114.0%. In brief, this work proposed a strategy to prepare a new type fluorescent imprinting polymer based on N-GQDs and provided an attractive perspective for the detection of protein by using the combination of N-GQDs and molecular imprinting technique.
Co-reporter:Tong Zhao, Xi-Wen He, Wen-You Li and Yu-Kui Zhang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 11) pp:NaN2394-2394
Publication Date(Web):2015/01/30
DOI:10.1039/C4TB02130D
Transferrin (Trf)-functionalized copper nanoclusters (Trf-Cu NCs) were fabricated as a novel red-emitting fluorescent probe for the targeted bioimaging of cancer cells. A one-pot approach was developed to prepare stable, water-soluble and red-emitting Trf-Cu NCs at room temperature via a biomineralization process with Trf as the template and ascorbic acid as a green reducing agent. Trf acted not only as a stabilizer and reducer, but also as a functional ligand for targeting the transferrin receptor. The as-prepared Trf-Cu NCs showed an intense red fluorescence with a red emission peak at 670 nm (quantum yield about 6.2%), suggesting that the probe could potentially be used for bioimaging in vivo. The developed Trf-Cu NCs had excellent photostability and water solubility and exhibited a high specificity to transferrin receptor with negligible cytotoxicity. The probe was successfully applied to the targeted bioimaging of HeLa cells.
Co-reporter:Xiao-Li Zhao, Dong-Yan Li, Xi-Wen He, Wen-You Li and Yu-Kui Zhang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 43) pp:NaN7582-7582
Publication Date(Web):2014/09/15
DOI:10.1039/C4TB01381F
In this study, we reported an epitope imprinting method on the surface of core–shell magnetic nanoparticles (NPs) for the recognition of target bovine serum album (BSA). The epitope was selected as the template molecule from the nonapeptide of surface-exposed C-terminus of BSA. The core–shell magnetic epitope molecularly imprinted polymers (Fe3O4@EMIPs) exhibited a specific capture activity for the corresponding target protein, BSA. The magnetic NPs made it easy to separate the imprinted material from solution by an external magnetic field, and the thin imprinted layer presented fast kinetics for the rebinding of the target protein. Moreover, the Fe3O4@EMIPs could separate BSA from the bovine blood sample. The epitope imprinting approach combined with magnetic NPs provided an easy and fast method for the specific recognition of BSA.
Co-reporter:Yan-Qin Wang, Ye-Yun Zhang, Fei Zhang and Wen-You Li
Journal of Materials Chemistry A 2011 - vol. 21(Issue 18) pp:NaN6562-6562
Publication Date(Web):2011/03/25
DOI:10.1039/C1JM10104H
In the present study, for the first time, without the help of any amphiphilic polymers or polymerizable surfactants, 3-mercaptopropionic acid (MPA) capped CdTe quantum dots (QDs) could be one-pot copolymerized into poly(N-isopropylacrylamide) (PNIPAM) microspheres during the monomer polymerization process just by controlling the synthesis temperature at two different polymerization stages. In the first stage, NIPAM monomers were initiated by potassium persulfate (KPS) below the lower critical solution temperature (LCST) to form PNIPAM networks with CdTe QDs distributed throughout. In the second stage, when the polymerize temperature was raised above the LCST, the PNIPAM networks collapsed to form spheres and the CdTe QDs were entrapped into the PNIPAM microspheres (denoted as CdTe–PNIPAM microspheres). Transmission electron microscopy (TEM) images showed that CdTe QDs have been successfully entrapped within the PNIPAM matrix. According to the dynamic light scattering (DLS) results, the CdTe–PNIPAM hybrid microspheres had a significantly narrow size distribution and their mean hydrodynamic diameter was about 267 nm. Compared with the original CdTe QDs, the CdTe–PNIPAM microspheres exhibited not only a prominent red-shift of their emission wavelength (as much as 36 nm), but also temperature dependent on–off fluorescence properties. Around the LCST, when the temperature was increasing, the fluorescence intensity decreased sharply; when cooling the solution, the fluorescence intensity would restore. Moreover, after repeated heating and cooling cycles, the photoluminescence (PL) quenching and enhancement processes were fully reversible around the LCST region.
Co-reporter:Fei Zhang, Xi-Wen He, Wen-You Li and Yu-Kui Zhang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 41) pp:NaN22257-22257
Publication Date(Web):2012/09/04
DOI:10.1039/C2JM33560C
In the last two decades, near-infrared (NIR) emitting Cu-doped quantum dots (QDs) have stimulated stupendous research interest for their excellent optical properties. Due to the synthetic method in the organic phase, almost none of the NIR emitting Cu-doped QDs were used as the fluorescent probes for biological imaging, despite being employed for applications in many fields. In this work, we successfully synthesized water-soluble Cu-doped CdS quantum dots (Cu:CdS d-dots) with an emission wavelength at 722 nm using a fast and facile hydrothermal method. The optical properties of the d-dots and several key parameters of the synthesis conditions such as dopant concentration, reaction temperature, reflux time, and especially the pH of the reaction mixture were systematically studied, and the mechanism of these parameters is also discussed. A red shift of the emission maximum as a consequence of the increased reaction temperature was observed, but it does not move to the NIR region until Cu2+ is doped even at the highest reflux temperature in aqueous solution. The d-dots have good water solubility and biocompatibility for successful labeling the living HeLa cells as fluorescence probe.
Co-reporter:Wei Zhang, Xi-Wen He, Ya-Qiong Yang, Wen-You Li and Yu-Kui Zhang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 3) pp:NaN352-352
Publication Date(Web):2012/10/17
DOI:10.1039/C2TB00022A
In this work, aminophenylboronic acid functionalized mesoporous silica coated CdTe quantum dots (APBA-coated QDs) were synthesized and applied to the selective capture and fluorescent quantification of glycoproteins. The as-prepared APBA-coated QDs, relying on the interaction between APBA and cis-diol containing structures, demonstrated excellent selectivity for the glycoproteins. Their high surface area and APBA-enriched silica matrixes give rise to faster binding kinetics and higher binding capacity for the glycoproteins, which further make them attractive for biomedical/chemical sensing applications. Based on the fluorescent properties of the particles, the as-prepared APBA-coated QDs were successfully applied to the fluorescence quantification of glycoproteins. The present study provides a facile strategy to fabricate functionalized fluorescent materials and is of great significance for isolation and detection of glycoproteins in proteomics.
Co-reporter:Fei Zhang, Ting-Ting Sun, Yan Zhang, Qiong Li, Chao Chai, Li Lu, Wen Shen, Jun Yang, Xi-Wen He, Yu-Kui Zhang and Wen-You Li
Journal of Materials Chemistry A 2014 - vol. 2(Issue 41) pp:NaN7209-7209
Publication Date(Web):2014/08/22
DOI:10.1039/C4TB00920G
Magnetic quantum dots (MQDs) are an important class of agents for fluorescence (FL)/magnetic resonance (MR) dual-modal imaging due to their excellent optical and magnetic properties. However, functional MQDs prepared by a simple room-temperature route as FL/MR dual-modal imaging probes are lacking. Herein, we report the fabrication of Gd-doped CdTe quantum dots (Gd:CdTe QDs) as an agent for FL/MR dual-modality imaging. The as-designed QDs with an ultrasmall particle size are synthesized by a facile one-pot aqueous synthesis approach at room temperature. They emit strong fluorescence at 640 nm with a quantum yield of 37% in water, and they have a high longitudinal relaxation rate (r1) value of 3.27 mM−1 s−1. With the further conjugation of folic acid, the Gd:CdTe QDs can successfully label live HepG2 cells for targeted cellular imaging and present no evidence of cellular toxicity up to the concentration of 0.5 mg mL−1. They have been employed as a suitable contrast agent successfully for tumor-targeted FL/MR dual-modal imaging in a mouse model.
Co-reporter:Ting-Ting Sun, Ming Wu, Xi-Wen He, Wen-You Li and Xi-Zeng Feng
Journal of Materials Chemistry A 2015 - vol. 3(Issue 34) pp:NaN6978-6978
Publication Date(Web):2015/08/04
DOI:10.1039/C5TB01209K
In the past two decades, Cu-doped inorganic semiconductors with near-infrared (NIR) emitting have garnered stupendous research interest. Nevertheless, the incompatibility between the NIR emitting and high photoluminescence quantum yield (PLQY) of the Cu-doped fluorescent probes restricted the extensive application in biological imaging. Herein, the water soluble Cu+ doped CdS quantum dots (Cu+:CdS QDs) were prepared by using a one step synthesis method in a N2 atmosphere. The d-dots possessed an ultra small size (∼5 nm), a high QY (25.6%), NIR emission (∼700 nm) and a low cytotoxicity because of which they were used as fluorescence probes. Besides, the study of the Cu d state and the mechanism of emission proposed the explanation for the fluorescence enhancement compared with previous reports. Moreover, the optimal conditions of dopants, stabilizers, sulfur ion concentration, pH, heating time and reflux temperature were also studied systematically to acquire best-quality Cu-doped nanocrystals. Due to the excellent optical properties and favourable biocompatibility, the Cu+:CdS QDs as fluorescence probes were successfully applied to label living 3T3 cells.
Co-reporter:Yang Liu, Gao-Fei Tian, Xi-Wen He, Wen-You Li and Yu-Kui Zhang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 7) pp:NaN1283-1283
Publication Date(Web):2016/01/13
DOI:10.1039/C5TB02322J
The development of ideal contrast agents was of great importance for multimodal imaging. However, the simple combination of different contrast components always needed long-time preparation and a tough reaction environment. In this study, we introduced a one-step microwave-assisted approach to synthesize lysozyme-capped gold nanoclusters (Lys–Au NCs) rapidly instead of traditional conditions. Irradiation with continuous microwave power shortened the reaction time from several hours to one hour and generated a large red shift (50 nm) of the fluorescence emission. The ultrasmall Lys–Au NCs showed excellent properties, including high quantum yield (19.61%), good stability, low cytotoxicity and good biocompatibility. This eco-friendly nanoprobe provided significant contrast signals in both NIRF (near-infrared fluorescence) and CT (X-ray computed tomography) in vivo imaging. Further conjugation with folic acid made the nanoprobe favorable for targeted fluorescence imaging of cancer cells and tumor-bearing mice.
Co-reporter:Wei Zhang, Xi-Wen He, Wen-You Li and Yu-Kui Zhang
Chemical Communications 2012 - vol. 48(Issue 12) pp:NaN1759-1759
Publication Date(Web):2011/12/07
DOI:10.1039/C2CC17200C
A thermo-sensitive imprinted polymer coating CdTe quantum dots was developed to prepare fluorescent thermo-sensitive protein-affinity materials, which exhibited high specific recognition ability towards target proteins.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 23) pp:
Publication Date(Web):
DOI:10.1039/C3AY41069B
A pH and temperature dual-responsive macroporous protein imprinted cryogel was synthesized by a facile “one-pot” method using N-isopropylacrylamide (NIPAAm) and 4-vinylphenylboronic acid (p-VPBA) as the main functional monomers. The smart molecularly imprinted polymers (MIPs) could recognize the target glycoprotein (ovalbumin (OB) as a template) dynamically and reversibly. The morphologies and features of the cryogels were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The rebinding and swelling experiments showed that the MIP cryogels could respond quickly to temperature and pH. Various parameters such as the pH value of the protein solution, adsorption temperature, and the rebinding time were optimized. Under the optimal conditions, a higher adsorption capacity and imprinting factor of the MIP cryogel were achieved, and were found to be 21 mg g−1 and 3.4, respectively. Moreover, the MIP cryogel exhibited good selectivity and acceptable regeneration capacity. A real sample analysis further demonstrated its feasibility for the target protein separation. These excellent performances suggested that the obtained imprinted cryogel should be a promising candidate for recognition and separation of OB.
Co-reporter:Yan-Qin Wang, Xi-Wen He, Wen-You Li and Yu-Kui Zhang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 11) pp:NaN2208-2208
Publication Date(Web):2013/01/22
DOI:10.1039/C3TC00681F
We fabricated QD–silica–Au NC hybrid spheres, in which the solid silica core contained QDs while the mesostructured silica shell contained Au NCs, by a two-step synthesis procedure. The hybrid spheres were further characterized by high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and nitrogen adsorption–desorption analysis to confirm the formation of the ternary hybrid structure. The as-prepared ternary hybrid spheres showed an interesting fluorescence spectrum variation and further could be developed as a precursor for fabricating multicolor fluorescence bar codes by using L-cysteine (L-Cys) as an effective post-encoding adjuster. A small variation of the concentration of L-Cys led to a prominent change of the precursor's fluorescence intensity ratio, which could correspond to a series of distinguishable multicolor fluorescent bar codes. Furthermore, the multicolour fluorescence bar codes fabricated by the post-encoding method showed excellent non-reversibility, batch-to-batch reproducibility of the intensity ratios, photophysical and thermal stability properties and anti-interference capabilities, which are important virtues for them to be used in high-throughput bio-labelling and imaging.
